Optical networks that operate in harsh environments such as those on military aircraft can benefit from networking equipment having Built-In-Test (BIT) functionality to assist in determining potential network failure points. A BIT functionality is generally not present in commercially available components. By adding a small number of high reliability low cost components in a novel manner to available or in development fiber optic transceivers, the ability to test transceiver functionality and fiber cable plant integrity can be achieved. This BIT approach is applicable to both multi-mode and single mode fiber optic networks. The following proposal will detail such an approach towards a BIT functionality and present a plan to demonstrate the technical feasibility of the approach. Benefit The proposed work will demonstrate the feasibility of Built-In-Test (BIT) technology for military and commercial avionic fiber optic networking equipment. The commercialization will benefit both the military and the public sector by enabling more reliable and easier to maintain communications systems on aircraft. Keywords Built In Test, Fiber Optic Networking, Optical Components, Avionics